Control device for stabilization of hydrofoils attached to water-craft



Sept. 1, 1964 H. VON SCHERTEL CONTROL. DEVICE FOR STABILIZA TION OF HYDROFOIL ATTACHED TO WATER-CRAFT 2 Sheets-Sheet 1 Filed Jan. 22, 1963 ooooooonc wrwx. w 7a United States Patent 3,146,751 CONTROL DEVICE FUR STABILIZATION OF HYDROFOILS ATTACHED TO WATER-CRAFT Hanns von Schertel, Hergiswil am See, Switzerland Filed Jan. 22, 1963, Ser. No. 253,148 24 Claims. (Cl. 114-665) The present invention relates to an automatic control device serving to maintain the immersion depth of fully submerged hydrofoils or hydrofoils of which only small parts are emerging, both being attached to water-craft and serving furthermore to reduce rolling and pitching motions as well as vertical accelerations of such craft in a seaway.

The invention represents a further development of US. patent application 67,189 which refers to hydrofoils having air-exit apertures on the foils suction side through which a controllable air quantity is admitted into the water flow in order to influence lift. The control of air which diminishes the foils lift with increasing air quantity admitted is effected on one hand by a sensor respond ing to variations of immersion depth and on the other hand by control devices which respond to the motions of the craft in a seaway.

This invention eliminates the disadvantages which still exist in the above mentioned patent application and improves functioning and eificiency of control. The disadvantages of the former application consist mainly in that the air regulating valve, described therein and by means of which the quantity of air which is admitted to the foil can be regulated and which in turn is controlled by control devices (sensors), can only influence a single row of air exit apertures on the foil. As experiments have shown, lift cannot be changed within a sufficiently large range by means of a single row of air exit apertures resulting in an inadmissibly large immersion and emergence which in turn lead to impacts of the hull with the wave crests on one hand an to aeration of the foils on the other hand, if the latter approach the Water surface too closely.

This disadvantage is eliminated by the present invention in such a manner that the air regulating valve when operating in the direction of lift decrease engages additional air exit rows on different locations of the foil section following a determined program and at the same time regulates the admitted air quantity. Preferably the control action is performed in such a way, the admission to an additional row of foil exit apertures is effected by the valve when the critical air quantity has been reached on the previously aerated row, a quantity being defined by the phenomenon that with its further increase the lift drops only little in relation to such air increase. On the other hand-in order to attain higher lift coefficients by the control deviceair exit apertures have also been provided on those parts of the foils lower surface on which a subpressure exists and to which by the valve action in the direction of lift increase air is admitted after all air outlet apertures on the foils upper surface have been closed. By this ventilating method the lift of the foil increases-contrary to the conditions of the foils suction side-with the increase of air quantity which is admitted to the lower foil surface.

In the U.S. patent application 67,189 two valves are shown in a design example which can influence the air quantities of two exit rows on the foil, however there does not exist a compulsory joint action in accordance with a fixed control program.

A further disadvantage of the arrangement of the valves in the former application can be seen in the fact that these air regulating valves due to their configuration will become immersed when the boat is at rest and are therefore exposed to mud and corrosion. This may in- 3,146,751 Patented Sept. 1;, 1964 fluence the reliabity of their proper function, especially because the control forces exerted by the sensors are extremely small unless one uses servo-motors for the transmission of signals which would involve complication. In order to eliminate these disadvantages in the present application, connecting channels have been provided in the struts (depth sensors) which lead the air from the valve, now arranged above the flotation water line, to exit apertures which extend over the span of the foil.

Furthermore an improvement of performance in a seaway is obtained by controlling the air admission to the foils in response to different signals and by different control means depending on the position of the foils on the craft. Air which is fed to the front foil is regulated jointly by the air valve controlled by the control devices and by a depth sensor, whereas the air which is fed to the rear foil is only regulated by valve which in turn is controlled by devices responding to the position and the motions of the craft in a seaway. The maintenance of lateral stability can be left entirely to the last mentioned control devices.

Finally the invention shows an improved hydrodynamic type of depth sensor in order to maintain unseparated fiow and to obtain a more exact and reliable control function.

The invention consists in that the hydrofoil is provided on its upper surface and, if indicated, also on its lower surface, at locations where a subpressure develops when moving through the water, with several rows of air exit apertures, one row behind the other, which wholly or partially span the width of the foil and lead to chambers inside of the foil and to which air is fed for the purpose of influencing the lift. This air quantity is regulated by a valve, preferably a sliding valve, arranged above the flotation water line, provided with a row of outlets, each of which is connected separately by a duct to one of the already mentioned foils exit rows. For each outlet opening on the valve, a coordinated inlet and a coordinated slide is provided, whereby all slides are interconnected in a predetermined position with respect to their outlets and are operated jointly by the control devices which respond to the position and to the motions of the craft in a seaway. For regulating the air quantity to the rear foils of the craft, the valve receives its air directly from the free atmosphere and thus the lift of the rear foil can only be controlled by the control devices, whilst the control of air quantity to the front foil is effected jointly by the valve and the depth sensor, which in the region of subpressure of its streamlined suction has air intake channels which are arranged one behind the other. These channels are provided with groups of air intake orifices, one group above the other, partly above and partly below foilborne water line, and whereby preferably each inlet at the valve receives its air separately from one of the said air intake channels, thus controlling the lift of the front foil jointly by the depth sensor and the control evlces.

Various embodiments of the invention are illustrated by Way of example in the accompanying schematic drawings FIGS. 111 as follows:

FIGURE 1 is a front view of hydrofoil with the main control elements on a hull shown in cross section;

FIGURE 1a is a plan View of the hydrofoils shown in FIGURE 1;

FIGURE 2 is a diagram of an arrangement of hydrofoils on a water-craft, shown from below;

FIGURE 3 is a diagrammatic view of another hydrofoil arrangement on a water-craft, shown from below;

FIGURE 4 is a diagrammatic view of yet another hydrofoil arrangement on a water-craft, shown from below, in which the front foil is of the surface piercing type;

FIGURE 5 is a diagrammatic sectional view of the control device for foils embodying the present invention which are only controlled by an air regulating valve, the direction of travel of the foil being from left to right and the air valve being depicted drawn at an enlarged scale;

FIGURE a is a vertical section of the foil at a distance from the control element in direction of travel;

FIGURE 51) illustrates the air valve of FIGURE 5 in cross section;

FIGURE 6 is a view similar to FIGURE 5 of the control for foils which are controlled by joint action of the depth sensor and the air valve;

FIGURE 7 is a diagrammatic sectional view of another embodiment of the control for foils which are controlled by the joint action of depth sensor and air valve, the air valve and the pressure controlled valve for air feed to the foils lower surface being depicted in a larger scale;

FIGURE 8 is a diagrammatic section view of yet another embodiment of the control for foils which are controlled by the joint action of depth sensor and valve;

FIGURE 8a is a fragmentary horizontal section view of the foil according to FIGURE 8;

FIGURE 9 is a sensor (foil strut) in side elevation;

FIGURES 9a and 9b are two foil sections of the depth sensor of FIGURE 9; and

FIGURE is an enlarged horizontal section view of the depth sensor taken along the line BB of FIGURE 9.

In the drawings identical parts of the structure in the several figures are marked by identical numbers.

In FIGURES 1 and 1a the main control elements are shown. Number 1 marks the fully submerged hydro foils, which in the example are provided with the air exit apertures 2a and 2b, the number of which however may vary according to requirements. The foils are connected to the hull by means of the struts 3 which are designed to act as depth sensors. Instead of the two split foils, one undivided foil can be provided at which separated groups of air exit rows 2 are arranged along the starboard and port side, thus enabling separate control of each half-foil. Inside the hull in a protected location the valves 4 are arranged above the flotation water line WLR. Into these valves lead the connecting ducts 7 or their pipes 5 respectively. The control devices which respond to the motions of the craft, are symbolized by the block 6. They are connected by connecting members 10 to the valve slides.

The depth sensor 3 is provided on its sides with a group of air intake orifices 9, shown on FIGURES 6-8, by means of which the subpressure generated at the foil sucks in air for discharge through the exit apertures 2, via the mentioned ducts in the strut 3, the valve 4 and the ducts 5, whereby the air quantity depends on the area of the orifices 9. Because the orifices which are below the water surface are cut-off from air entry by the later described method, air can only enter through the free open orifices above the water surface, the area of which increases With decreasing immersion depth of the foils, thus reducing the lift in a recovery sense, by the increase in the quantity of air which is led to the foil. By the valve 4, inserted in the connection between the intake orifices 9 and the exit apertures 2, the air quantity which is led to the valve by the depth sensor, can either be increased or decreased. The depth sensor can be dispensed with for the rear foil air quantity control, because the immersion depth of the rear foil is only influenced by the valve 4 which receives air directly from the free atmosphere.

The different arrangement of the foils 1 on the hull and the control principle which is provided for each foil according to its position on the hull can be derived from FIGURES 2-4. The front foils which are influenced by the depth sensor as well as by the valve which is controlled by the control device are marked by thick solid lines.

FIGURE 2 shows in the front part of the ship two split up foils which can also be arranged as one undivided foil whilst only one foil of lesser span is provided in the aft of the ship. The air quantity fed to the front foils is controlled by the sensor as well as by the valve. The air quantity however which is admitted to the rear foil, is controlled only via the valve by control devices which respond to trim and trim-angle velocity and, if desired, to accelerations of the aft of the ship, thus effectively reducing pitching motions of the craft in a seaway.

With respect to rolling motions, the transversal stability is achieved by the two immersion-depth controlled front foils (or front foil half sections). Hereby the commands given by control devices in order to reduce the rolling motions are superimposed to those of the depth sensor, i.e. the air quantity for each of the two foils is influenced by both control systems. Whenever it should be desirable to exclude the influence of the water surface as far as possible and to maintain lateral stability solely or chiefly by the control devices (gyroscopes) in order to obtain the most effective stabilization of rolling motions, then a control according to FIGURE 8 can be used. Immersion depth control can also be arranged in accordance with the modified FIGURE 6, described later on.

FIGURE 3 shows only one foil 1 of the fore part of the ship, whilst two split up foils are provided aft-ships which can also be united in one continuous foil. With this foil arrangement the air quantity which is fed to the front foil is regulated by the depth sensor as well as by the valve. However the air quantity which is admitted to the rear foil is only controlled via the two valves by control devices which respond to the motions and the position of the craft. The flying height of the boat is therefore only maintained by a single depth sensor on the bow of the craft, whilst longitudinal and lateral stability is maintained irrespective of the water surface by the control devices. This kind of stabilizing system which from all specified examples requires the most simple control device, is similar to the second specified system of FIGURE 2 except that there the stabilizing rolling moments are not produced by the rear foil, but by the front foil.

FIGURE 4 shows a combination of a fully submerged rear foil, controlled by control devices, with a surface piercing V-foil on the foreship which maintains its immersion depth automatically in the well known manner i.e. stabilizes the flying height. The foil parts which, when travelling are above the water surface, are marked by broken lines. The configuration of this front foil however is such that the foil does not have sufiicient lateral stability which would enable it to maintain the lateral position of the craft and therefore the moments at the rear foil, which are caused by the variation of admitted air, can effectively influence the lateral position of the vessel. For producing the rolling moments the exit apertures on the rear foil are arranged separately on the star-board and portsides and their air supply is controlled by two separate valves which are controlled by control devices which in turn respond to heeling angles and rolling anglespeed of the craft in a seaway. Lateral stability is thus maintained jointly by front and rear foil resulting in a much smoother ride in a seaway as compared to the uncontrolled surface piercing foil system. In addition to that, the described foil arrangement allows an effective stabilization in a seaway which in boats with surface piercing foils of sufficiently high lateral stability can only be obtained in a restricted measure. The combination with a surface piercing foil offers the advantage that in case of a failure of the control adequate lateral stabilization by the increase of immersion depth (in consequence of reduction of angle of attack or speed) can be taken over by the front foil alone.

The efiiciency of the described control can of course be increased by admitting a controlable air quantity to the front foil, especially if its inherent stability is reduced to a minimum. The control of the air quantity is effected in the same manner as on the front foil in FIGURE 2 whereby preferably a configuration of a control device in conformity with FIGURE 8 (or FIGURE 6) is adopted.

The sequence in which the exit rows of the foil are supplied with air by the valve, and the method of control (throttling or opening) which occurs when the slide rod is shifted depends on the position of the various slides in relation to their coordinated exit apertures. By suitable arrangement any desired control program can be obtained for air admission, be it to the upper or lower foil surface separately or jointly to both of them. In the following the two most important methods are described by which the valve can control air admission. For better understanding of the figures the closing directions of the valves are marked by arrows which also mark the consecutive order in which the outlets are throttled in FIGURES 5, 7 and 8.

Method Number 1 In order to regulate the quantity of air admitted to the rows of air exit apertures, either on the upper foil surface alone, or on the lower surface alone, the slides in the valve have the same position in relation to their outlets, thus causing simultaneously closing or opening of all outlets whenever the slides are working. The arrangement can be seen from FIGURE 5b in which the slides 8a3c occupy identical positions in relation to their outlets 3aI3c in the slide valve 4.

If the air admission towards the exit rows on the upper and lower foil surface is controlled jointly by the valve, as in FIGURES 5b and 6, the group of slides 811-80 (FIGURE 5b) and 8b, 8c (FIGURE 6) in the slide valve 4 is arranged relative to the outlets 13b, 130 or 13a, respectively, to the foils upper surface in such a manner that in the mean position of all combined slides (medium lift), they open with their edges, which point in closing direction, a part of the associated outlets, provided that air to the inlets of the valve is admitted from the free atmosphere (as in FIGURE 5b) and that they open the total area of the outlets if air is admitted via the air intake orifices of the depth sensor (as in FIGURE 6), whereas the group of slides for the outlets 13a to the lower foil surface (only one slide 811 is shown in the FIGURES) with their edges which point in the opening direction, overlap the outlets by a distance corresponding to the part of the outlet which has been opened by each slide of the other group (Sa8c). The lengths of the slides are such that with all outlets to the upper foil surface being opened, all outlets to the lower foil surface are closed and vice versa, that is, with the full opening of all outlets to the lower foil surface, all outlets to the upper foil surface are closed. With this method of air admission, all outlets to the upper foil surface are simultaneously throttled if the slides move in the direction of lift increase and thereupon all outlets to the lower foil surface are simultaneously opened.

Method Number 2 In this method, represented by the FIGURES 5 and 7, in order to simplify it, the connecting ducts 7a-7c and 7a lead from the outlets lite-13c and 131: of the sliding valve 4 in the same sequence to each one of the chambers 1211-120 and 12a in the foil 1. For regulating the air quantity admitted to the exit apertures either on the foils upper surface alone or on its lower surface alone, the slides in the valve are arranged in such a way that in their mean position (medium lift) the slide 8c opens with its edge, which is pointing in the closing direction, the outlet 130 (to which in FIGURE 7 corresponds 13) at least to such an extent that the critical air quantity is fed to the most rearward row of air exit apertures 2c on the foil and that each slide (8b-8a) of the forward placed outlets 13b, 13a is progressively staggered in relation to its outlet by at least part of the outlet length (length of outlet in longitudinal valve-axis) in the closing direction of the valve, provided that the valve receives its air directly from the free atmosphere, as in FIGURE 5, whereas each slide is progressively staggered further in relation to its outlet in the opening direction, provided that the valve receives its air via the air intake orifices of the depth sensor as in FIGURE 7, thus preferably an exit row on the foil receives air only if the previous one is supplied at least with the critical air quantity.

If air admission to the exit apertures on the foils upper surface and lower surface is controlled jointly by the valve 4, then the combined slides in their mean position are in such a location in relation to their outlets, that slide releases with its edge pointing in the closing direction at least a part of the rearmost outlet to the foils upper surface, whereas slide 811 (FIGURE 5) of the rear-most outlet 13a (FIGURE 5) to the foils lower surface with its edge pointing in the opening direction overlaps its outlet by the total closing path of the other outlets. FIGURE 5 shows only one outlet to the foils lower surface, corresponding in its position to the rearmost outlet, if several outlets are provided, whereas in the system depicted in FIGURE 7 there are shown no slides and outlets to the foils lower side, which correspond to this method of control. Each slide, pertaining to the outlets 13a, 13b in FIGURE 5 and to the outlets 13c, 13b in FIGURE 7 is progressively staggered in relation to its outlet by at least apart of the outlet length and this in the direction of closing at the outlets of the foils upper surface, if the corresponding inlets, as in FIGURE 5, receive air directly from the free atmosphere and in the direction of opening, if the corresponding inlets receive air via the air orifices of the depth sensor, as depicted in FIGURE 7, whereas the slides of the outlets to the foils lower side are correspondingly staggered in the direction of opening. The slides are of such length, that with all outlets to the foils upper surface being fully opened, all outlets to the foils lower surface are closed and that vice versa in full-open position of all outlets to the lower surface, all outlets to the upper surface are closed. If with this control method the valve is operated from full opening in the direction of lift increase, all outlets to the upper surface are closed one after the other from front to rear, provided that the valve receives air directly from the free atmosphere, whereas they are throttled from rear to front, provided air enters via the depth sensor and thereupon the outlets to the lower surface are opened one after the other from the rear to front. The ventilation sequence from rear to front offers for both surfaces the advantage that the rear-most exit row, which alone is open during normal cruising, gives the most favourable lift/drag ratio to the foil.

The reason for the reversed ventilation sequence of the exit rows on the foil by the valve which is in connection with the depth sensor is explained later on. The second method described above is the preferred method of air quantity control.

The foremost row of air exit apertures to the foils upper surface is preferably excepted in the described method of control. The embodiment of control parts for this row can be seen from the FIGURES 58. The connecting duct 7a between the outlet 13a of the valve 4 to the foremost air exit apertures 2a (chamber 12a) is provided with a group of air intake orifices (9a) one above the other and located below the normal foilborne water line. The outlet 1311 at the valve is completely closed by its slide 8a when all combined slides are in their mean position whereby the two edges of slide 8a are at such a distance from its outlet, that the latter is not opened in the operation direction of lift increase and that in the operation direction of lift decrease it is preferably only opened after the other outlets, provided that the valve receives air directly from the free atmosphere (as in FIGURE 5) and is opened preferably before the other outlets, if the valve is connected to the air intake openings of the depth sensor as shown in FIGURE 8. In the embodiments of FIGURES 6 and 7 in which the valve is also connected to the depth sensor, the slide 8a opens outlet 13a simultaneously with the other outlets.

The purpose of this arrangement is to avoid too close an approach of the foil to the water surface which might cause aeration of the foils upper surface. Throttling of air entry by the valve to row 2aas it is possible to other rows-is impossible and therefore the foil is aerated, uninfiuenced by the control, through the emerging intake orifices 9a via the exit apertures 2a (FIGURE 5a) when the admissible minimum depth is underpassed. It is however possible to admit an additional air quantity via the inlet 11a even when the air intake orifices 9a are below the water surface which is of importance for a predicted airregulation by the control device. The air intake channel 7a can be connected to a second chamber with air exit apertures to the upper foil surface or an additional duct 7 can be also provided with air intake orifices, as in FIG- URE 5 (duct 7b) in order to protect the foil still more effectively against too close approach towards the water surface.

The figures, on which the two control methods of the valve are applied, are now described in detail.

FIGURE 5 shows the embodiment of the control in which the air quantity passing through the exit apertures 2 on the foil 1 is only controlled by the control device 6 which operates the valve 4, which received its air influx from the free atmosphere. This arrangement, as described, serves to control hydrofoils which are attache to the rear part of the craft.

The rows of air exit apertures 20, 2b and 2c, arranged one behind the other, are provided on the upper surface of the foil (FIGURE 5 which extend over the entire span of the foil or part of it and which lead into the chambers 12a, 12b and He. The number of air exit rows can be chosen at will. On the lower foil surface only one row of air exit apertures is provided, which can also extend over the entire foil span or part of it and which lead into the chamber 121:. On the lower foil surface however, 'aIso two or more exit rows can be arranged. The foil section can be of any suitable shape which generates, when travelling, a sufiiciently high subpressure in the region of the air exit apertures. If exit apertures are provided on the sections lower side, sufiiciently high increment velocities must occur in the region of the applied angle of attack on those parts of the foils lower surface on which the air exit apertures are arranged in order to warrant the draining-off of the admitted air (biconvex sections).

In the foil strut 3, which in the present form of control is not adapted as an immersion depth control element, there are provided ducts 7a, 7b, 7c and 7u for each chamber 12a, 12b, 12c and 12a, which lead the air from the valve 4, located above the flotation water line WLR, to the chambers I2.

The valve 4 is shown in all embodiments as a sliding valve. In a synonymous manner it can of course take the form of a rotary slide valve, without deviating from the nature of the invention or changing the function of the control. For each row of air exit apertures 2 on the foil 1 are provided air inlet openings 11, leading directly to the free atmosphere, an outlet 13 and a control slide 8 (which in a rotary valve is rotatable). The slides have a common housing and all slides are connected with each other by a slide rod and can be operated jointly by the control device 6. The shifting forces for the valve 4 are extremely small enabling in most cases direct control by the control device, without the need of inserting electric or hydraulic amplifiers which is an important advantage of this new control system.

To the already described slide arrangement of FIGURE must be added that-when decreasing the distance by which the slides for the control of the lower foil surface in their mean position protrude beyond their exits with their forward edges-there results an overlapping of airoutlet on the upper foil surface with the beginning of air admittance to the lower surface, that is to say the lower surface is already aerated before the air outlet to the upper surface is cut off.

In all the valves, shown in the figures, each slide serves 8 to equalize the pressure inside a chamber which is enclosed between two slides in order to avoid the occurrence of axial forces which in turn would increase the operating forces.

It is obvious that the length of the valve 4 can be com siderably shortened by the application of several small inlet and outlet openings at the valves periphery or by annular inlet and outlet channels.

The slide rod which connects the slides with each other in their described positions, leads to the control devices, which in FIGURE 5a are symbolized by the block 6 and which are described in my earlier United States patent application 67,189. The operation direction of slide action of the valve 4 is chosen in such a way that-when the craft leaves its horizontal longitudinal or lateral axis or its flying altitudethe valve slides of a downward moving foil or foil halves are shifted by the device in the direction of lift increase, whereas the valve slides of an upward moving foil or foil halves in the direction of lift decrease, thus producing recovering vertical forces or moments. In order to stabilizer the rear foil, a gyroscoping horizon and rate gyros (described in U.S. patent application Serial No. 67,189) are used which react to trim and trim angle speed and accelerometers which reduce the vertical accelerations. If the lateral stability is maintained by one or two rear foils, as in FIGURE 3, the valves of the starboard and the port-foil are additionally influenced in opposed directions by a gyroscoping horizon for maintaining lateral stability and by a second rate gyro which responds to the rolling angle velocity.

FIGURES 6 to 8 show forms of embodiments of the control in which the air quantity discharged through the exit apertures 2 on the foil 1 is controlled jointly by the control device 6, which operates the valve 4 and by the depth censor 3. This device serves in the described manner to control hydrofoils which are attached to the forward part of the craft.

With this control system the air in FIGURES 6 and 7 is not sucked in directly through the inlet openings 11 of valve 4, but via the air intake orifices 9 of the superpositioned depth sensor, which controls the influx of air quantity according to immersion depth. The precontrolled air quantity passing through the valve can again be throttled or augmented therein, that is to say, the air quantity which is discharged at the foil and which influences lift and depth of immersion, is determined by the superimposed signals of the depth sensor and the valve.

FIGURE 6 shows the form of embodiment in which the valve, as in FIGURE 51;, influences simultaneously first the admission of air to the air exit rows of the upper foil surface and then the lower foil surface.

The depth sensor 3 the principle of which has already become known by the U.S. patent application 67,189 and WhlCh is preferably formed as a center strut, as in FIGURE 1, is of streamlined sections. In FIGURE 6 are provided 1n this control element three air intake channels 1941- (their number however may be varied at will), one behind the other, which are provided with groups of air in take orifices 9a-9c arranged one above the other partly above and partly below the foilborne water line. The groups of air intake orifices can be arranged in sequence one above the other one or overlapping, which refers especially to those of the foremost located group 9a and the following next higher located group 9b. The measure of overlapping is preferably chosen such that like with the control method of the valve of FIGURE 5 air feed to one row of air exit apertures 2 begins if the row to the rear of it is fed with the critical air quantity. It is obvious that-deviating from FIGURE 6the highest located group of intake orifices 9c can also be provided for the foremost channel and the lower located group 9a for the rear most channel. The channels 19 with their intake orifices 9 are located in the forward part of the sensors section wherewhen travelling-the orifices are cut-off from air entry by the subpressure, caused by the water flow, if they become immersed below the watersurface. In FIGURE 6 therefore air can only get into the duct 7c a via the valve through the orifices which are above the water surface.

The hydrofoil 1 is, as in FIGURE a, provided with chambers 12a-12c into which, lead rows of air exit apertures 2a-2c on the upper foil surface, whereas the chamber 1211 is fitted with a row of air exit apertures 2u on the lower surface. The number of rows of air exit apertures can also be chosen at will.

The valve 4 has a separate outlet for each row of air exit apertures 2a-2c and Zn on the foil 1 (FIGURE 5a) and a corresponding inlet opening Ila-11c and 111: like the already described valves of FIGURE 5 and FIGURE 5b. However in FIGURE 6 for each inlet connected with the sensor 3 a corresponding additional airintake 14b and Ida is provided, by means of which the air quantity flowing via the sensor towards the air exit apertures on the foil can still be increased. For reasons which have already been described, no additional air intake is provided on the valve for the foremost air exit aperture 2a at the upper foil surface.

The air inlets 11b and 11c on the valve are connected to the air intake channels 1% and 190 in the sensor 3 in such a manner that the uppermost group of air intake orifices 90 on the sensor leads to the rearmost row of exit apertures 2c on the upper foil surface (FIGURE 5a) and the next lower located group 91) on the sensor to the second rearmost row 2b of the upper foil surface and so on if further exit rows are provided on the upper surface. By this arrangement-in case of depth increase which has to cause a lift increase-the air which is admitted to the exit rows 2rz-2c of the upper foil surface, is throttled and then cut-off analogous to the process in the valve (FIG- URE 5)in the favorable sequence, beginning from the foremost row 2a to the rearmost row 20. When travelling at foil borne water line at least the rearmost row 2c is aerated. In all following examples the same configuration and the same scheme of connection are provided for the depth sensor.

The additional inlets 14b and 140 of valve 4 have in this embodiment such a position with regard to their slides Sb and 8a thatwhen all the combined slides are in their mean position-they are fully overlapped and are directly behind the slides edges, pointing in the closing direction, thus they are all simultaneously opened. The additional inlets however, can advantageously be arranged in such a way that at the combined slides mean position, all additional inlets 14 are completely covered by their slides 8, whereby the inlet slide, which is connected to the lowest group of intake orifices on the sensor is with its edge, pointing in the closing direction, closely before the inlet, and that the slide of each following additional air inlet being connected with the next higher located group of intake orifices on the sensor, is always spaced from its inlet opening with its edge pointing in closing direction, by at least that part of the outlet length which admits the critical air quantity. The additional ventilating of the rows on the upper foil surface, therefore, takes place in sequence from the front to the rear, that is in the opposite direction than in the arrangement shown in FIGURE 5, which is conditioned by the described scheme of communications of these rows with the air intake orifices 9 on the depth sensor 3. It is obvious that the admission of air through the valve becomes effective only on those air exit rows of the foil, the corresponding intake orifices 9 of which on the sensor are below water surface and to which therefore no air is admitted by the sensor. In its method of ventilation air is at first fed to the foremost row of air exit apertures, the air intake orifices of which on the sensor are located the lowest below the water surface, and then to the next following row with the next lowest air intake orifices on the depth sensor.

For the same reason the closure of the exit rows at the foil by the valve takes place from the rearward one to the front one in case that its inlets are connected with the depth sensor. It is obvious that in this case throttling becomes only eflective on such rows, the corresponding intake orifices of which on the sensor are located above the water surface, which applies to the rearmost row, the group of orifices of which on the sensor are in the highest location.

FIGURE 6 contains two additional slides 8h, one at each end of the valve, which-as in all the following embodiments-serve only as pressure equalizers, if the righthand face of slide 8a or the left-hand face of slide 8h are under pressure.

From FIGURE 6 and its description can be seen that by the joint operation of valve and depth sensor, only the air influx to the foils upper surface can be influenced, whilst aeration of the lower surface is controlled only by the valve, which means a simplification of the system. In the embodiment according to FIGURE 7 however, the air influx to both foil surfaces is controlled by both control elements jointly. For the proper function of this installation the depth sensor requires the insertion of a pressure-controlled valve, becausein accordance with the described efiect of aeration of the lower surfacethe air quantity ought to be increased with the increase of immersion of the sensor, whilst the sensor in the described form on the contrary diminishes the air influx with in creasing immersion depth.

In FIGURE 7 the immersion depth sensor 3 is shown in the same arrangement as in FIGURE 6, except how ever, that an air intake channel 19a with the group of intake orifices 9a has been added for air-feed to the lower foil surface. The arrangement of the chambers 12 and its air exit apertures 2 on the foil 1 is also the same as in FIGURES 5, 5a and 6. The valve 4 is provided as in FIGURE 6, for each row of exit apertures 2a2c and Zn on the foil (FIGURE 5a) with a separate outlet each 13- 13c and 13a a corresponding inlet 1111-110 and Hit as well as a corresponding additional air entry 14b, 14c and 1411 for each inlet which is connected with the depth sensor.

In further conformity with FIGURE 6 the rearmost row of exit apertures on the upper foil surface is connected via the valve with the uppermost group of air intake orifices on the sensor (except 9) and the exit row in front of it with the next lower arranged group 9b and so on. The uppermost added group of air orifices 9u however, is connected via the valve with the already mentioned prasure controlled valve 16. The outlet 13a therefore does not lead-as beforedirectly to the chamber 12, but first to the pressure-operated valve 16, which in turn is provided with an outlet 17 which is connected to the chamber 121! and its corresponding row of exit apertures 2a. The later described valve 16 controls the exit row 2a at the lower foil surface in such a way that an increasing quantity of air is fed via the valve to the lower surface when the immersion of the orifices 9b! increases. By this scheme of communication-with decreasing immersion depth-the air exit rows of the upper foil surface become aerated one after the other beginning with the rearmost and ending with the foremost row, whereas with increasing immersion the exit rows of the lower surface are aerated in the same order. The aeration of the lower surface begins with increasing immersion only after the termination of air influx to the upper surface, provided that the lowest orifice 9u is arranged above the highest orifice 90, but it already begins before the closing of the air influx to the upper surface if both rows are overlapping each other.

The pressure-control valve 16, in FIGURE 7, comprises a control cylinder 21b and a counter-pressure cylinder 21a, the pistons of which 2212 and 22a-which may be preferably in the form of roll-diaphragm pistons-are connected by tension rods 23b and 23a to a double-armed lever 24, supported in 29, thus the piston forces are opposed to each other. The arms of the lever are of unequal length and form an obtuse angle. The piston of the control cylinder 21b is connected to the longer lever arm. The double-armed lever may also have arms of equal length if the control cylinder 2112 has a larger diameter than the counter-pressure cylinder 21a. Furthermore instead of the shown double-armed lever, two spiral curve discs can be used, which are connected with the piston by means of flexible tension elements and whichwhen turningcause a change in the lever arm between tension direction and rotation axis 29. The cylinder 21a is connected by the duct 15a to the suction orifices 25:: which are constantly below the water surface. These orifices are provided on the strut (depth sensor) in the vicinity of the foil and are therefore subjected to a high subpressure when the boat is in motion. The cylinder 21b is also connected via duct 15b to suction orifices 25a, which are provided in a vertically staggered position in relation to 25a. It is however, also connected with the group of air intake orifices 914 via the duct 26, which leads to the outlet 1311 on the valve and from the corresponding inlet opening 11a to the air intake channel 1%: in the depth sensor 3. The piston 22a is coupled with the slide 28 in the valve 27 which controls air entry from the inlet 13 to the exit apertures 2L! (FIGURE 5a) on the lower foil surface, 2811 is again a presspure equalizing slide.

At normal immersion at foilborne condition, the air intake orifices 9a are above the water surface and air can flow from these orifices to the suction orifices 2512. Because the total area provided for the intake orifices 9a is great in relation to the area of the suction orifices 2%, only little subpressure is generated in the ducts 26 and b and in the control cylinder 21b. In spite of the great leverage on the double-armed lever 24-, the subpressure is not able to overcome the force which is exerted by the opposing piston 22a, which is under the influence of the full subpressure at the suction orifices 25. Due to the suction force acting upon it, the piston 22a is moved until it stops at the cylinder head and the slide 28 connected to the piston completely closes the outlet 17, which is a longitudinal slot, and thereby prevents air exit to the lower foil surface. However, if the immersion depth increases to such an extent that part of the air intake orifices 9 in the depth sensor is immersed and cut-oif from air entry, then the totail air entry area is reduced in relation to the constant suction area which results in an increase of subpressure in the ducts and in the control-cylinder 21b. The force of the piston 22b acting upon the longer lever arm now exceeds the opposing force of the piston 22a, thus pulling it forward and thereby the slide 28 opens the air inlet 1% and the outlet 17 of the valve and admits air to the foils lower surface. Since however with the motion of the pistonsdue to the position of the double-armed lever-the lever arm between the direction of the tension rod 231) and the rotation axis 29 is shortened and the lever arm between the direction of the tension rod 23a and the rotation axis lengthened, the motion comes to a standstill after a certain path as soon as the two moments exerted about the rotation axis 29 are in balance. Therefore, to every immersion of the sensor 3 within the range of the intake orifices 9 or to every throttle position of the slide 3% in the valve 4 corresponds a definite position of the slide 28 in the valve 27, which in turn corresponds to a definite air quantity, admitted to the exit apertures Zu on the lower foil surface.

If several rows of air exit apertures are provided on the lower foil surface, then the valve 27 will be provided with the corresponding number of outlets 17, air inlets l8 and of slides 28, whichas in FIGURE 5bare arranged in relation to their outlets in such a manner that all exit apertures on the lower foil surface experience equal aeration of which, according to FIGURE 5, are arranged in such a manner that the rows are fed with air one after the other, beginning with the rearmost row and ending with the foremost one. It should be emphasized that the control valve 16due to the condition of equilibrium between the two pistons 22a and 22bdoes not I2 respond to pressure changes on the suction orifices 25a and 255, which occur with speed variation of the craft.

In the example, the slides 8 of the valve 4 are arranged in accordance with the second control method. The slide 8a regulating the pressure-controlled valve thereby takes the same position in relation to its outlet 1314, which in the preceding description is provided for the rearmost outlet to the upper foil surface. If the combined slides are shifted in the closing direction (lift increase) then at first the outlet 13a is being overlapped by its slide, which results in the opening by the valve 16 of air entry towards the row of exit apertures Zu (FIG- URE 5a) to the lower foil surface orin case that several exit rows are providedto such exit rows. Thereupon the air entry to the exit rows 20 and 2d on the upper foil surface is throttled and cut-off, beginning on the rear row and ending on the front row. In the opposite operation direction, during which the additional air entry inlets are opened, the inlet to the lower foil surface is blocked by the pressure-controlled valve 16, even if the intake orifices 9:: on the sensor should be immersed during action.

FIGURE 8 depicts a third embodiment, in which the regulation of the admitted air quantity to hydrofoils which are attached to the fore body of the craft is effected jointly by a valve and a sensor. It ditfers from the embodiment of FIGURE 6 and FIGURE 7 in that the depth sensor controls only air exit rows which extend along the inner or the middle part (undivided foil) of the span on the upper foil surface, whereas the valve controls only air exit rows which extend along the outer part of the span on the upper foil surface and which extend on the lower foil surface at least along the outer part or preferably also along the total span. With this very simple form of control in which the flying height of the craft is only controlled by the front foil inner parts, these latter giveeven if two separate front foils are provided-a relatively low lateral stability and therefore the outer lying parts of the foils which are influenced via the valve by the control devices are able to maintain-on account of their great lever arm to the crafts longitudinal axisetfectively the lateral position and to overcome the rolling moments which are generated by the effect of the immersion depth stabilization. The following described control method is therefore, as already mentioned, especially for foil arrangements in accordance with FIGURES 2 and 4.

In FIGURE 8 the depth sensor 3 is provided with the air intake channels 19a19c, fitted with groups of intake orifices 9a-9c and leading directly to the chambers Ila-12c in the foil. The chambers extend only along the inner part 11' of the front foil orif the foil is undividedalong its middle part and which are provided with air exit apertures (FIGURE 5a) to the foils upper surface. Preferably the air intake channel with the highest located group of intake orifices 9c lead to the rearmost exit row of apertures 20 on the upper foil surface and the next lower located group on the next channels always to the corresponding next forwardly arranged exit row on the foils upper surface. Air entry to the upper surface of the inner part of the foil is therefore controlled only by the depth sensor in relation to immersion in such a manner that according to the arrangement of the group of intake orifices in the foilborne water line only the rearmost row will be aerated with the critical or full quantity of air and the next row in front of it at the utmost with a small quantity.

The valve 4 in FIGURE 8 is in its preferred form, as in FIGURE 5, formed for an air-feed sequence of the air exit rows from rear to foreward, but the slides can be also arranged according to FIGURE 5b in such a manner that simultaneous air influx to all rows occurs. The connecting ducts 711-70 lead to the chambers 12a'12c which extend only along the outer part In of the front foil (see also FIGURE 1) and the air exit apertures of which discharge to the upper foil surface. Furthermore the connecting duct 7r: leads to the chamber 12a with exit apertures to the lower foil surface extending at least along the outer part of the span, preferably however along the entire span, in order to increase the lift influence of the lower surface which is controlled by the valve 4 only. In order to simplify the induction of the ducts into the foil chambers, the inner and outer part of a chamber are separated and somewhat set-off against each other, as shown in FIGURES 8 and 8a (120, 12a etc.). Each chamber, however, can also receive a partition wall and the ducts from depth sensor and valve can be led to either side of it. It is also possible-without deviating from the principle of the control in accordance with FIGURE 8to provide chambers which with their air exit apertures extend over the entire span and which are aerated separately and preferably one chamber by the sensor and the next following one by the valve.

Preferably another valve 34 can be connected to or combined with valve 4 which controls the entry of additional air to the intake channels 19 of the sensor and which together with the valve 4 is operated by the control devices 6. By this arrangement, the air quantity controlled by the depth sensor can still be increased for the purpose of lift decrease which is of importance in order to avoid an excessive approach of the foil to the water surface in a seaway. The valve 34 of FIGURE 8 shows again the same staggered arrangement of the slides of the valve, according to FIGURE 5, however analogous to the valve 4 of FIGURE 7, in the reversed aeration sequence. That is to say that-when operating the valve in direction of lift decreaseadditional air is first fed via air inlet 14a. to the foremost row 2a and then to the rows behind it in the order in which they follow each other. For the valve 34 the slide arrangement of FIGURE b can also be chosen, although with reduced effectiveness.

The control principle of FIGURE 8 in which the immersion depth control does not contribute to lateral stability can also be attained by the embodiment of FIG- URES 6 and 7, FIGURE 6 shows the additional installation which has the efiect that a foil on each side of the craft or one undivided foil with two depth sensors, one at each side of the vessel, do not respond any longer to heeling, thus lateral stability can be maintained by the control devices by means of the valves only. The additional installation is so that always identical intake channels (leading to identical exit rows of the foil) on the two depth sensors 3 are connected with each other before entering into the valve by means of the ducts 45' (in FIGURE 6 represented by broken lines), that is the intake channel 191') of the starboard foil via the duct 46b with 1% of the portfoil and the intake channel 190 of the starboard foil with 19c of the portfoil via the duct 45c. Thereby identical exit rows on the starboard and port foil receive at every lateral inclination the same air quantity, the latter being controlled by the total number of intake orifices and both intake channels which are freed above the water surface. In other words the two sensors respond to their mean immersion depths. The intake channels 19a of both sensors are preferably not connected to each other, again in order to safeguard the foils against too great a decrease of immersion depth. In the ducts 45, stopcocks 46 coupled with each other or coupled slide valves are inserted by means of which the air flow passages can be jointly regulated. By throttling the connection between the two sensors, the lateral stability of the craft is again taken over by the sensors to any desired degree. For example if the control devices are out of order or in calm water when the mentioned control devices can be disconnected. This arrangement therefore presents great advantages. With combined depth sensors the valve 4 remains fully eliective as well.

It goes without saying that all effective combinations on the basis of the given examples are possible without deviating from the nature of the invention.

The described valves of FIGURES 6-8 which serve to control the air quantity, fed to the foils, which are attached to the fore body of the craft, can be controlled by a number of control devices, mainly by the device described in the U.S. patent application Serial No. 67,189 which respond to the relative immersion speed of the depth sensor in relation to the water surface and a verticalaccelerometer which prevents the contouring of short waves by the foil. In the foil arrangements according to FIGURES 2 and also 4, by which the lateral stability is maintained entirely or party by the front foil, the valves of the starboard and port foil are influenced in an opposing sense by the gyroscopic horizon and by a rate gyro which responds to rolling angle speed.

In cases where the operating force of the control devices is not sufficient for activating the valve 4, as must be expected, for example in an arrangement according to FIGURE 8 on account of the great number of slides, a new form of amplifier 31 (servo-motor) is shown in FIGURE 8 which is inserted between the control device and the valve. It receix'es its operation energy by the flow forces on the moving struts or foils and is of such simple design that the advantage of the control-especially with regard to superfluousness of electronic or hydraulic power sourcesis not lost. The amplifier 31 is formed by the control cylinder 32 connected with the slide rod 10, and by the piston 33, the piston rod 35 of which is attached to the fixed point 36 on the craft. Exits 37 are provided at each cylinder end which lead crosswise to the control valve 38, the latter being rigidly connected with the cylinder 32 and being provided with two slides 39, which are actuated by the control devices 6 via the rod iii. The suction duct 41 which is flexible in its upper parts and enters into the valve between the two slides leads to the suction orifices 4-2. which are provided on the depth sensor 3 in the vicinity of the foil and in the subpressure region of the sensors section.

In the mean position of the slides 8 and the control device 6 the two slides 39 of the control valve 38 overlap the exits to the cylinder 32, thus preventing the subpres sure between the two slides 39 from reaching the cylinder. If the control devices 6 shift the rod it) with the slides 39 for example to the right, then the left part of the cylinder chamber becomes connected with the subpressure space and the right part of the cylinder chamber with the free atmosphere which causes a joint movement of the cylinder 32 with the slides 8 and the control valve 38 in the same direction. The parts move to the right until the outlets of the control valve 38 are again overlapped by their slides, that is to say they traverse the same path which the rod 1% has covered (follow-up control).

The turn control which is described in the United States patent application 67,189 and which serves to cause in- Ward banking of the craft in turning circles is effected by the new and improved control installation, as shown in FIGURE 6. The housing of the valve 4 is longitudinally movable in the supports 43, fixed on the craft and connected by the connecting element 44 to the disc with a helical cam groove as disclosed in patent application Serial No. 67,189. All ducts leading to the valve are-at least in their upper partprovided flexible. The sense of operation of the installation is chosen in such a way that with the turning of the disc, the housing of the valve of the foil on the outer side of the curve is moved in the direction of lift increase (to the left) and that one belonging to the valve of the foil of the inner side in the direction of lift decrease (to the right).

Instead of the compulsory operation by the disc which is connected with the directional control, the valve housing can also be shifted by means of a curve sensor 56 (sensing centrifugal force), shown in FIGURE 8, in such a manner that the craft takes a coordinated inward banking position automatically. The curve sensor 56 is composed of the cylinder 57, rigidly attached to the boat, with its piston 47 which is connected by the connecting elements 48a and 48b with the valve housings of the starboard and port foils. The outlets 49 on both cylinder ends lead to the control valve 59 which has the same configuration as the control valve 38 in FIGURE 8. The control valve 50 is connected by the rod 51 with a movable mass or pendulum 52 which is held in its mean position by the spring 53. The pendulum, the movements of which in both directions are limited by two stops 54 to the length of the valve opening path, can also be connected to a damp device 55. The direction of the pendulum movement is at right angles to the crafts longitudinal axis, that is to say, all valves are arranged as in FIGURE 1 and the depth sensor must be imagined to be turned 90 in the direction of travel. All ducts leading to the valve 4 must again be flexible in order to ensure freedom of motion of the valve housings.

Assuming that FIGURE 8 is viewed from the rear in the direction of travel (excepting the depth sensor) and the boat is in a left turn, then the following function of the curve sensor results: the left turn generates a centrifugal force to the right of the drawing by which the pendulum 52 with the slide of the control valve Ell is shifted in the same direction until it rests against the stop 54. The subpressure to which the cylinder space to the right side of the piston 47 is thereby exposed, shifts the piston with the housing of valve 4 to the right until the effect of the centrifugal force on the pendulum ceases. Since the operating sense of both valves is chosen in such a manner that the valve on the outside of the curvei.e. the starboard valve shown in FIGURE 8when shifting the housing to the right increases the lift and that the valve on the inside of the curve (not shown in the drawing) reduces the lift, the craft will be banked towards the center point of the curve until the boat is in the heeled position which is coordinated to the turn at which centrifugal force and the transverse component of the pendulums mass outbalance each other. Then the pendulum returns to its mean position and the position of the valve 4 in relation to the slide 8 is maintained during a stationary curving travel of the craft. If the radius of the curve is increased, for example in order to return to a straight travelling direction, then the transverse component of the pendulums mass exceeds the centrifugal force which is exerted upon it and the pendulum comes to rest on the left stop, whereby the control valve t connects the cylinder space on the left side of the piston with the subpressure regions until the boat returns into the heeled position which is coordinated to the more flattened curve or into the erect position which corresponds to travelling in a straight direction. The device also controls the slides in valve 4 in a recovering sense when the craft is heeling whilst travelling straight ahead.

In order to enable the helmsman of the craft to adjust the flying height of the boat, for example in order to decrease in a calm sea the strut drag of the front foil (and thereby also of necessity the immersion depth of the rear foil), adjusting gears are provided between the turn control device (disc with cam groove, curve-sensor) and the casing of valve 4, by means of which the length of the connecting element 44 in FIGURE 6 can be altered. This causes a displacement of the valve casing and a change of the air quantity, admitted to the front foil and thereby a change of lift. The flying height changes until by the emerging or immersion intake orifices, the air quantity for normal lift is again admitted to the foil. Every known mechanism which causes a displacement can be used for the adjusting gears 58 in FIGURE 6, for example a spindle on the connecting element 44 which fits into the inner thread of a conical tooth wheel which can be rotated by a second bevel gear by means of the flexible shaft 59, which leads to the control stand on the bridge of the craft. Depending on the operation of the adjusting gears 58 of the starboard and port valve in the 16 same or in an opposing sense independent of the automatic control the flying height can be altered or a list can be produced in order to equalize wind pressure.

FIGURE 9 shows a hydrodynamically favorable embodient of the depth sensor 3 (strut). Its leading edge is forwardly inclined, that is to say the part of the leading edge which is above the water surface forms an acute angle with that surface. Hereby the spray generated at the surface piercing point of the sensor is reduced and the angle which it forms with the surface is diminished, which improves the accuracy of the control action. In order to attain as large an inclination as possible of the sensors leading edge, without making the chord of the upper part of the sensor too great, this upper part which is only immersed at the take-off of the craft as well as the lowest not emerging part of the sensor can be nearly perpendicular, as shown in FIGURE 9.

FlGURE 9a shows an advantageous section for the depth sensor. It is a symmetrical circular arc section with referably blunt trailing edges and a very small leading edge radius. Such a section has only a very flat overpressure region at its head, thus the spray which is caused by that overpressure is slight. The blunt trailing edge compels the flow to follow the contours of the section which is essential for the proper function of the control. FIGURE 91) shows a preferred section, the leading edge of which is wedge-shaped and which leads in a concave curve into the convex central part of the second (S-curvature), which furthermore reduces the overpressure although it extends over a longer range. This shape of section develops the least spray.

The section of FIGURE 10 shows an embodiment of the arrangement of the air intake orifices on the depth sensor whereby the cross-section follows the line 13-13 through an orifice (FIGURE 9). The orifices 9 which lead into the channel 12 are in this embodiment pierced in a wall which forms the front part of scallop-shaped recesses 60 in the sensor. This front wall is arranged at nearly right angles to the contour of the profile. The direction of air entry is form the rear slanting forwards. This arrangement serves a double purpose, the first one being to protect the orifice, when travelling, completely against clogging up by floating foreign substances. The other one is to prevent the entry of water particles into those orifices which during travel are located near the water surface, where the subpressure reigning below the water surface decreases to Zero. Because the kinetic energy of the water flow does not permit a strong deflection of the current, the air intake orifices are covered by the flow already at small immersion depth. It is also possible to provide small scallop-shaped protruding parts 61 in front of the recesses in order to obtain a stronger flow deflection. The air intake orifices are arranged on both sides of the depth sensor in order to reduce control disturbances which may be caused by short-time flow separation at oblique flow direction.

What is claimed is:

1. Control device for hydrofoils attached to water craft and being provided on the foils upper surface in the region, at which subpressure is generated during travel, with plural rows of air exit apertures, one behind the other and extending at least partly over the foil span, a plurality of chambers inside of the foil connected with said apertures to which air is admitted, for the purpose of influencing lift, valve means for regulating such air arranged above the flotation water-line, said valve means being provided with a series of outlets, each of which is connected separately by a duct to a row of said air exit apertures on the foil, said valve means being provided for each outlet with a coordinated inlet opening and a coordinated valve slide, means interconnecting all of the valve slides in a predetermined position with respect to their outlets and adapted to operate the valve slides jointly responsive to control devices which respond to the position and to the motions of the craft in a seaway, further means for regulating the air quantity to a front foil of the craft including a depth sensor having air intake channels, said valve inlet openings receiving air from said intake channels, said channels being arranged one behind the other, in a region of subpressure on the depth sensor and being provided with groups of air intake orifices arranged one above the other, partly above and partly below the foilborne water line, whereby the lift of the front foil is controlled jointly by the depth sensor and the control devices.

2. Control device for hydrofoils attached to water craft and being provided on the foils upper surface in the region, at which subpressure is generated during travel, with plural rows of air exit apertures, one behind the other and extending at least partly over the foil span, a plurality of chambers inside of the foil connected with said apertures to which air is admitted for the purpose of influencing lift, a sliding valve for regulating such air, arranged above the flotation water-line, said valve being provided with a series of outlets, each of which is connected separately by a duct to a row of said air exit apertures on the foil, said valve being provided for each outlet with a coordinated inlet opening and a coordinated slide, means interconnecting all slides in a predetermined position with respect to their outlets and operating the same jointly responsive to control devices which respond to the position and to the motion of the craft in a seaway, said valve inlet openings communicating directly with the free atmosphere for controlling the air quantity to the rear foils of the craft.

3. Control device for hydrofoils attached to water craft and being provided on the 'foils upper surface in the region, at which subpressure is generated during travel, with plural rows of air exit apertures, one behind the other and extending at least partly over the foil span, a plurality of chambers inside of the foil connected with said apertures to which air is admitted for the purpose of influencing lift, a sliding valve for regulating such air, arranged above the flotation water-line, said valve being provided with a series of outlets, said valve being provided for each outlet with a coordinated inlet opening and a coordinated slide, means interconnecting all slides in a predetermined position with respect to their outlets operating the same jointly responsive to control devices which respond to the position and to the motions of the craft in a seaway, a depth sensor, provided in the region of subpressure on its section with air intake channels, arranged one behind the other, said channels being provided with groups of air intake orifices, one above the other, arranged partly above and partly below the foilborne waterline, means directly connecting said air intake channels to said rows of air exit apertures of the forwardmost foil of the craft, extending only along the central part of the span of the upper foil surface, means connecting the air outlets on the valve to rows of said air exit apertures extending only along the outer parts of the upper foil surface and at least along the outer parts of the lower foil surface.

4. In a control device for hydrofoils, the combination recited in claim 1, wherein, in order to regulate the air quantity admitted to several air exit rows of the upper foil surface or the lower foil surface, all combined slides in said valve have the same position in relation to their outlets.

5. In a control device for hydrofoils, the combination recited in claim 1, wherein, in order to regulate jointly the air quantity admitted to several air exit rows on the foils upper and lower surface, the group of slides in the valve for the outlets to the upper foil surface are arranged in such a manner that in the mean position of all combined slides said group of slides open with their edges which point in closing direction at least part of said ou lets, said group of slides for the outlets to the lower foil surface with their edges pointing in the opening direction overlap said outlets by a distance corresponding to the 18 part of the outlet which is opened by each slide of the other group, the slides having such lengths that with all the outlets to the upper foil surface being opened all outlets to the lower foil surface are closed and with all the outlets to the lower foil surface being opened all outlets to the upper foil surface are closed.

6. In a control device for hydrofoils, the combination recited in claim 1, wherein, in order to regulate the quantity of air admitted to several rows of exit apertures on the upper foil surface, arranged one behind the other, the connecting ducts between the outlets on the valve and each row of air exit apertures on the foil lead to said rows in their consecutive order and whereby the combined slides in the valve are arranged in such a manner that in their mean position, the slide for the rearmost outlet completely opens said outlet with its edge pointing in closing direction, and that each slide of each consecutive outlet in front of it is progressively staggered in relation to its outlet by at least part of the outlet length in the closing direction of the valve.

7. In a control device for hydrofoils, the combination recited in claim 2, whereby in order to regulate the air quantity admitted to several air exit rows on the upper or lower foils surfaces alone, the connecting ducts between the outlets on the valve and each row of air exit apertures on the foil lead to said rows in their consecutive order and wherein the combined slides in the valve are arranged in such a Way that in their mean position the slide for the rearmost outlet with its edge pointing in the closing direction opens the outlet at least to such an extent that the critical air quantity is admitted to the rearmost row of air exit apertures and that each slide of each consecutive outlet in front of it is progressively staggered in relation to its outlet by at least part of the outlet length in the closing direction of the valve, whereby a row of air exit apertures on the foil receives air admittance only if at least the critical air quantity is flowing towards the preceding row.

8. In a control device for hydrofoils, the combination recited in claim 1, wherein, in order to regulate jointly the air quantity admitted to several air exit rows on the foils upper and lower surfaces, the connecting ducts between the air outlets of the valve and each row of air exit apertures on the upper and lower foil surface lead to said rows in their consecutive order and the combined slides in their mean position are located in relation to their coordinated outlets in such a way that the slide of the rearmost outlet to the upper foil surface completely opens said outlet with its edge pointing in closing direction, whereas the slide of the rearmost outlet towards the lower foil surface with its edge pointing in closing direction overlaps said outlet by a distance corresponding to the closing path of the outlets towards the upper foil surface, and the slides for each consecutive outlet are progressively staggered in relation to their outlet openings by at least part of the outlet length in the direction of closing, whereby the slides are of such length that with all outlets towards the upper foil surface fully opened all outlets towards the lower foil surface are closed, and with all outlets towards the lower foil surface fully opened all outlets to the upper foil surface are closed.

9. In a control device for hydrofoils, the combination recited in claim 2, wherein, in order to regulate jointly the air quantity admitted to several air exit rows on the upper and lower foil surfaces, the connecting ducts between the outlets of the valve and each air exit row on the upper and lower foil surface lead to said rows in their consecutive order, and the combined slides in their mean position are located in relation to their coordinated outlets in such a way that the slide of the rearmost outlet to the upper foil surface opens with its edge pointing in closing direction the associated outlet at least to such an extent that a critical air quantity is admitted to the rearmost row of air exit apertures on the foil, whereas the slide of the rearmost outlet to the lower foil surface with its edge pointing in closing direction overlaps the associated outlet by a distance corresponding to the closing path of the outlets towards the upper foil surface and the slides for each consecutive outlet to the upper foil surface located in one axial direction therefrom are progressively staggered in relation to their outlet openings by at least part of the outlet length in the direction of closing, and that the slides for each consecutive outlet in the same axial direction to the lower foil surface are progressively staggered in opening direction, whereby the slides are of such length, that with all outlets to the upper foil surface fully opened, all outlets to the lower foil surface are closed and with all outlets to the lower foil surface fully opened, all outlets to the upper foil surface are closed.

10. In a control device for hydrofoils, the combination recited in claim 1, wherein, the connecting duct in said depth sensor between an air outlet on the valve to the foremost row of air exit apertures on the upper foil surface is provided with a group of air intake orifices, one above the other and below the foilborne water-line and said last mentioned outlet on the valve being fully overlapped by its slide when all combined slides are in their mean position, said slide being of such length that the outlet is not opened in the operating direction of lift in crease.

11. In a control device for hydrofoils, the combination recited in claim 2, wherein the foil is attached to the water-craft by a foil strut, the connecting duct between an outlet on the valve and the foremost row of air exit apertures on the upper foil surface being located in said foil strut and being provided with a group of air intake orifices, one above the other and below the foilborne water-line.

12. In a control device for hydrofoils, the combination recited in claim 1, wherein each air inlet opening on the valve, the corresponding outlet of which leads to a row of air exit apertures on the upper foil surface, excepting the outlet to the foremost row, is connected with an air intake channel in said depth sensor in such a sequence that the uppermost group of air intake orifices on the sensor leads to the rearmost row of exit apertures on the upper foil surface and each next lower located group on the sensor leads to each consecutive row in front of said rearmost row on the upper foil surface, and wherein said valve is provided for each inlet opening, which is connected to the depth sensor, with a corresponding additional air intake, which with all combined slides in their mean position is fully overlapped by the slide, and said intake being located directly behind the edge of said slide pointing in closing direction.

13. In a control device for hydrofoils, the combination recited in claim 1, wherein each inlet opening on the valve, the corresponding outlet of which leads to a row of air exit apertures on the upper foil surface, excepting the outlet to the foremost row, is connected with an air intake channel in said depth sensor in such a sequence, that the uppermost group of air intake orifices on the sensor leads to the rearmost row of exit apertures on the upper foil surface and each next lower located group on the sensor leads to each consecutive exit row in front of said rearmost row on the upper foil surface, and whereby the valve is provided for each inlet opening, which is connected to the depth sensor, with a corresponding additional air intake, which with the slides in their mean position is located in such a manner, that all additional air intakes are fully overlapped by their slides, wherein the slide of the inlet, which is connected to the lowermost group of intake orifices on the sensor is placed with its edge pointing in closing direction closely before the inlet, and the slide of each following additional air inlet, which is connected to the next higher located group of intake orifices on the sensor, being progressively spaced from its inlet opening with its edge pointing in closing direction 29 by at least that part of the outlet length which admits the critical air quantity.

14. In a control device for hydrofoils, the combination recited in claim 1, including a pressure-controlled valve, each row of air exit apertures on the lower foil surface being connected with an outlet of said pressure-controlled valve, said pressure-controlled valve including a slide which opens the outlets thereof in relation to the amount of subpressure to which said pressure-controlled valve is subjected and each air inlet on said air regulating valve means, excepting the one leading towards the foremost row of exit openings on the upper foil surface, is connected with an air intake channel in the depth sensor and with said pressure-controlled valve in such a way that the uppermost group of air intake orifices on the sensor leads to said control cylinder of said pressurecontrolled valve, the second uppermost group on the sensor to the rearmost exit row on the upper foil surface and each consecutive lower located group on the sensor to each consecutive forwardly located exit row on the upper foil surface.

15. In a control device for hydrofoils, the combination recited in claim 3, wherein said valve is coupled with a second valve for the purpose of controlling additional air, said second valve having outlets separately connected to the intake channels in the depth sensor and which for each outlet is provided with a corresponding air inlet and a corresponding slide.

16. In a control device for hydrofoils, the combination recited in claim 1, wherein the quantity of air admitted towards several rows of exit apertures on the upper surface of the front foil is regulated jointly by the valve and the depth sensor, said craft having port and starboard depth sensors each having intake channels and air intake orifices, the groups of air intake orifices of said port and starboard depth sensors being in equal position and leading to equal exit rows on the foils, being connected with each other before entering the associated valve, each by a duct, the intake channels of the lowermost air intake group being unconnected and each duct being provided with a throttle valve, which valves are all coupled to one another to be regulated jointly.

17. In a control device for hydrofoils, the combination recited in claim 1, wherein an amplifier is arranged between the control devices and the sliding valve, said amplifier comprising a cylinder with a rigidly attached control valve having outlets which are connected crosswise to inlet openings on both ends of the cylinder, said cylinder being connected with the slides of said valve and having a piston rod attached to a fixed point on the craft, and said control valve being provided with two interconnected slides to be operated by control devices and which in their mean position are overlapping the said outlets, and said control valve being provided with an inlet between said slides, said inlet being connected by a duct with suction orifices provided on the depth sensor in the region of subpressure.

18. In a control device for hydrofoils, the combination recited in claim 1, said hydrofoils including port and starboard hydrofoils and wherein said valve means include sliding valves for each of said port and starboard hydrofoils having moveable housings connected to a directional control of the craft in such a manner that, during turns of the craft, the housing of the valve associated with the foil located on the outerside of the curve is moved in the direction of air throttling and the housing associated with the foil located on the inner side of the curve is moved in the direction of air increase.

19. In a control device for hydrofoils, the combination recited in claim 1, wherein the leading edge of the depth sensor, at least within the range of mean variations of immersion, is forwardly inclined so that said leading edge with its part above the water surface forms an acute angle with the water surface and said leading edge being generally wedge-shaped in section providing sides extend- 21 ing along a concave path into a convex central part of the depth sensor.

20. In a control device for hydrofoils, the combination recited in claim 1, wherein the air intake orifices on the depth sensor are arranged in the front wall of scallopshaped recesses formed in said depth sensor, said wall being nearly perpendicular to the contour of the depth sensor surface, said orifices pointing rearwards, and the intake orifices for an intake channel being arranged on both sides of the depth sensor.

21. In a control device for hydrofoils, the combination recited in claim 14, wherein a pressure-controlled valve is provided between the depth sensor and the rows of air exit apertures on the lower foil surface, including a control cylinder and a counter-pressure cylinder, the pistons of which are connected by tension rods to an unequal double-armed rocker element, the arms of which are forming an obtuse angle facing towards said cylinders, said connection being made in such a manner, that the piston forces are opposed to each other and that the tension rod of the control cylinder is connected to the longer lever arm of the rocker element, said cylinders being connected by ducts to separate suction apertures, located in the subpressure region of the depth sensor, and the control cylinder being furthermore in connection by a duct with an air intake channel in the depth sensor with air intake orifices, arranged one above the other, through which an air quantity is admitted, which changes with changing immersion depth, corresponding to the number of air intake orifices being at times above the water surface, and thereby changing also the subpressure in the control cylinder space, whereby one or more slides of a valve are connected to one of said pistons, said slides being located in relation to their outlets such that they are operated in the opening direction with increase of subpressure.

22. In a control device for hydrofoils, the combination recited in claim 1, said hydrofoils including port and starboard hydrofoils and wherein said valve means include sliding valves for each of said port and starboard hydrofoils having moveable housings connected to the piston of a cylinder, controlled by a control valve, the outlets of which are connected to the inlets on both cylinder ends, said control valve being provided with two interconnected slides, which in their mean position are overlapping said outlets and said control valve being provided with an inlet between the slides, said inlet being connected by a duct with suction orifices, located in the subpressure region on the depth sensor and whereby the slides of said control valve are connected to a mass, preferably a pendulum, movable in the transversal axis of the craft and held by a spring in its mean position, the movements of said mass being limited by two stops, whereby said mass can also be connected to a damping device.

23. In a control device for hydrofoils, the combination recited in claim 18, whereby adjusting gears are provided on the connection elements between the turn control device and the movable housings of said sliding valves for adjusting the length of said connecting elements in order to influence the crafts flying height and list, said adjusting gears being provided with an actuating element for communication with the pilot stand.

24. In a control device for hydrofoils, the combination recited in claim 2, wherein the regulation of the air quantity admitted to the rear foils is effected by a valve, said foils being combined with a V-shaped surface piercing front foil, the submersed span of which is too small in relation to its transversal foil inclination in order to maintain the lateral stability of the craft alone, thus lateral stability being maintained jointly by the combined action of the controlled rear foils and the surface piercing front foils.

References Cited in the file of this patent UNITED STATES PATENTS 2,709,979 Bush et al. June 7, 1955 3,006,307 Johnson Oct. 31, 1961 FOREIGN PATENTS 715,880 Great Britain Sept. 22, 1954 549,266 Italy Oct. 9, 1956 

1. CONTROL DEVICE FOR HYDROFOILS ATTACHED TO WATER CRAFT AND BEING PROVIDED ON THE FOIL''S UPPER SURFACE IN THE REGION, AT WHICH SUBPRESSURE IS GENERATED DURING TRAVEL, WITH PLURAL ROWS OF AIR APERTURES, ONE BEHIND THE OTHER AND EXTENDING AT LEAST PARTLY OVER THE FOIL SPAN, A PLURALITY OF CHAMBERS INSIDE OF THE FOIL CONNECTED WITH SAID APERTURES TO WHICH AIR IS ADMITTED, FOR THE PURPOSE OF INFLUENCING LIFT, VALVE MEANS FOR REGULATING SUCH AIR ARRANGED ABOVE THE FLOTATION WATER-LINE, SAID VALVE MEANS BEING PROVIDED WITH A SERIES OF OUTLETS, EACH OF WHICH IS CONNECTED SEPARATELY BY A DUCT TO A ROW OF SAID AIR EXIT APERTURES ON THE FOIL, SAID VALVE MEANS BEING PROVIDED FOR EACH OUTLET WITH A COORDINATED INLET OPENING AND A COORDINATED VALVE SLIDE, MEANS INTERCONNECTING ALL OF THE VALVE SLIDES IN A PREDETERMINED POSITION WITH RESPECT TO THEIR OUTLETS AND ADAPTED TO OPERATED THE VALVE SLIDES JOINTLY RESPONSIVE TO CONTROL DEVICES WHICH RESPOND TO THE POSITION AND TO THE MOTIONS OF THE CRAFT IN A SEAWAY, FURTHER MEANS FOR REGULATING THE AIR QUANTITY TO A FRONT FOIL OF THE CRAFT INCLUDING A DEPTH SENSOR HAVING AIR INTAKE CHANNELS, SAID VALVE INLET OPENINGS RECEIVING AIR FROM SAID INTAKE CHANNELS, SAID CHANNELS BEING ARRANGED ONE BEHIND THE OTHER, IN A REGION OF SUBPRESSURE ON THE DEPTH SENSOR AND BEING PROVIDED WITH GROUPS OF AIR INTAKE ORIFICES ARRANGED ONE ABOVE THE OTHER, PARTLY ABOVE AND PARTLY BELOW THE FOILBORNE WATER LINE, WHEREBY THE LIFT OF THE FRONT FOIL IS CONTROLLED JOINTLY BY THE DEPTH SENSOR AND THE CONTROL DEVICES. 